PROJECT SUMMARY Individuals from Hispanic/Latino backgrounds have a 50% increased risk of Alzheimer's disease (AD) compared to non-Hispanic white individuals. With the changing demographic trends in the United States, the prevalence of AD in the Hispanic/Latino population is expected to increase nine fold over the next 50 years. In addition to the patient, the burden of AD takes a significant toll on the families of loved ones with dementia, their communities, and the healthcare system. The difference in prevalence of AD is rooted in social disparities rather than differences in genetic vulnerability between Hispanic/Latino and white populations. It is critical to identify the specific social determinants in Hispanic/Latino populations that can be leveraged to develop culturally informed interventions that aim to maintain cognitive health and slow or prevent the progression toward mild cognitive impairment and clinical dementia. Midlife is a particularly important, yet understudied, period of the lifespan for cognitive aging. Prevention and intervention efforts are likely to be more effective if started before significant neuropathology accumulates in the brain. The objective of this proposal is to identify midlife factors and associated processes that contribute to health disparities in cognitive decline and risk of dementia. We will leverage an existing longitudinal study of midlife adults ? the California Families Project ? to couple more than 10 years of repeated assessments across middle adulthood with new data collection on the risk/protective factors and cognitive outcomes. This project will test socioeconomic (e.g., education, financial hardship), personality (e.g., neuroticism, conscientiousness), social (e.g., discrimination, social support), and acculturation (e.g., cultural values, acculturative stress) risk/protective factors for cognitive functioning in midlife Hispanic/Latino adults and the behavioral (e.g., physical inactivity, smoking), psychosocial (e.g., depressive symptoms, delay discounting), and physiological (e.g., inflammation, cellular biomarkers) mechanisms that explain these associations. This work will lead to new knowledge on midlife predictors of cognition and risk of AD, identify social determinants and pathways that create and sustain health disparities for Hispanic/Latino populations, and point to new prevention and intervention targets for promoting healthy cognitive aging in midlife and beyond.